The Occupational Studies Section conducts epidemiologic studies to identify occupational and other causes of cancer. During the past year, several investigations focused on cancer risks from agricultural exposures. Associations between several insecticides and non-Hodgkin's lymphoma (NHL) were observed among men and women. No clear associations were observed with 2,4-D and atrazine, two widely used herbicides. NHL and multiple myeloma were linked with work in metal, textile, and plastic industries. Diffuse NHL was more strongly associated with exposure to benzene and other solvents than was follicular NHL, which was excessive among workers exposed to oils and greases. Lung cancer was excessive among silicotics previously employed in the dusty trades in North Carolina. Risk of bladder cancer was elevated 150-fold among those heavily exposed to benzidine, but risks among fast and slow acetylator phenotypes were similar. Personal use of hair dyes appeared to increase the risk of NHL and multiple myeloma among men and women from Nebraska. Risks were greater among those who used dark, permanent dyes. Multiple myeloma was also associated with use of hair dyes among men from Iowa. Cigarette smoking was associated with leukemia. Physical activity on the job was inversely associated with cancer of the colon, prostate, and cervix. A computerized job exposure profile was developed to facilitate documentation of quantitative exposure assessments in cohort studies. Currently under investigation include studies of pesticides, benzene, methylene chloride, acrylonitrile, formaldehyde, asbestos, silica, and methodologic investigations to improve exposure assessments. Occupational groups with complex exposures include farmers, industrial workers in Turkey, pesticide applicators, firefighters and embalmers.